Shrestha Govinda, Briar Shabeg S, Reddy Gadi V P
Department of Research Centers, Western Triangle Agricultural Research Center, Montana State University, Conrad, MT, USA.
PeerJ. 2018 Nov 1;6:e5892. doi: 10.7717/peerj.5892. eCollection 2018.
The wheat stem sawfly (WSS), Norton, is an important wheat pest in the Northern Great Plains of the USA. No single control measure effectively suppresses WSS damage. This study provides information on the effects on the WSS adult settling preference behavior on wheat plants under laboratory conditions from treatment with both synthetic plant defense elicitors (Actigard and -jasmone) and a botanical insecticide (Azadirachtin). In addition, field experiments were performed to determine whether these chemicals impact the WSS fitness (larval mortality and larval body weight), winter wheat plant fitness (infestation, stem lodging, yield, and quality), adult population of WSS and spp., and larval parasitism levels. Our lab results showed that there were no significant differences in adult settling behavior on plants exposed separately to each chemical and control. In contrast, when adults were exposed simultaneously to treated and untreated plants, there was a significant reduction in the percentage of adults settling on Actigard and Azadirachtin treated plants compared to plants sprayed with water in the same cage. However, in field situations, regardless of application timing and field location, none of the chemicals significantly reduced adult population or stems damage. The exception was two times applications of Actigard had significantly lower WSS infested stem damage levels at 30 days after initial treatment applications at Knees and 50 days at Choteau locations compared to control, but without effect at the Conrad location. The field study indicated that two times applications of Actigard significantly increased diapausing larval mortality percentages and lowered stem lodging levels compared to untreated controls at Knees and Choteau locations, while no effects at Conrad location. Larval body weight was significantly lower in plots treated with Actigard at Knees and Conrad, but no effects at Choteau. No significant differences were found in wheat yield and quality in plots treated with chemicals and controls at any location. spp. adult population and parasitism levels were not negatively affected by the use of chemicals. In conclusion, this study offers insights on what treatments should be emphasized in more detail despite variable findings.
小麦茎蜂(WSS),诺顿,是美国大平原北部一种重要的小麦害虫。没有单一的控制措施能有效抑制小麦茎蜂的危害。本研究提供了在实验室条件下,合成植物防御激发子(阿噻菌胺和茉莉酮)和一种植物源杀虫剂(印楝素)处理对小麦茎蜂成虫在小麦植株上的定居偏好行为影响的信息。此外,还进行了田间试验,以确定这些化学物质是否会影响小麦茎蜂的适合度(幼虫死亡率和幼虫体重)、冬小麦植株适合度(侵染、茎倒伏、产量和品质)、小麦茎蜂和其他物种的成虫数量以及幼虫寄生水平。我们的实验室结果表明,单独接触每种化学物质和对照的植株上,成虫的定居行为没有显著差异。相比之下,当成虫同时接触处理过和未处理过的植株时,与在同一笼子里喷水处理的植株相比,在阿噻菌胺和印楝素处理的植株上定居的成虫百分比显著降低。然而,在田间情况下,无论施药时间和田间位置如何,这些化学物质均未显著减少成虫数量或茎部危害。例外情况是,与对照相比,在膝盖处初次施药后30天以及乔托处50天时,两次施用阿噻菌胺显著降低了小麦茎蜂侵染茎的危害水平,但在康拉德处没有效果。田间研究表明,与膝盖处和乔托处未处理的对照相比,两次施用阿噻菌胺显著提高了滞育幼虫死亡率百分比并降低了茎倒伏水平,而在康拉德处没有效果。在膝盖处和康拉德处,用阿噻菌胺处理的地块中幼虫体重显著较低,但在乔托处没有影响。在任何位置,用化学物质处理的地块和对照地块的小麦产量和品质均未发现显著差异。其他物种的成虫数量和寄生水平未受到化学物质使用的负面影响。总之,尽管结果存在差异,但本研究为应更详细强调哪些处理方法提供了见解。